Need HELP with new amp selection

i am new to subs,amps and all that stuff. I am looking to replace my old sony setup for obvious reasons and am looking at putting in a Kicker DCVR12. I have two questions, the first being the kicker comes in both 2 and 4 ohms, if i want to run it off 1 amp which is the best? second question is i currently hav a sony XM1S amp which has a maximum output power: 1 Ch x 600W at 4 ohm and maximum output power: 1 Ch x 900W at 2 ohm. if i want to run the DCVR12 to a good level will i need to replace the sony amp with a more powerful amp?

I am upgrading my system from front to back and the only thing I'm unsure about is amp selection for my subs. I have a Lanzar Vibe241. It is a 1000watt amp pushing 250rms x 2@ 4ohm and 420rms x 2 @ 2ohm.It's a great amp,don't get me wrong,but I'm getting ready to throw 2 JBL P1224 400rms subs in,and I'm looking to wire them to 2ohm for optimal power. As much as I like my Lanzar,I am becoming aware that they are a fairly low grade make. What type of amp would deliver the best slap as well as SQ and still give me 400-450rms x 2 @ 2ohm? For that matter,should I even worry about upgrading my amp or is the Vibe 241 a quality line considering it's Lanzar?